<!DOCTYPE html>
<html>
  <head>
    <meta charset="UTF-8" />
    <title>4.理解组件的data为什么是函数</title>
  </head>
  <body>
    <script type="text/javascript" >
      let data = function() {
        return {a:1}
      }

      data().a = 999
      console.log(data().a)
     
    </script>
  </body>
</html>